Radiation therapy or radiotherapy, often abbreviated as RT, RTx, or XRT, is a therapy applied in cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator (linac), particle accelerator, or radioactive source (teletherapy). RT is also used in treating many other medical conditions, including those where control of the immune system and inflammation is required. Historically, radiotherapy devices such as medical linear accelerators have employed several fixed radiation output rates when delivering treatments. In modern dynamic arc treatments, output rates and the motion of system components such as the accelerator gantry and collimators may be synchronized so that the planned dose is delivered as the mechanical configuration of the machine is continuously adapted to be consistent with the treatment plan. At present, all linear accelerators in use for external beam radiation therapy operate in relatively low duty cycle pulsed mode (e.g., pulse widths of the order of 1/1000th of a pulse repetition period). Also, variation exists between the radiation output contained in each pulse. This may lead to inaccuracies in the amount of output radiation dose delivered during a specific time period, and also to wild fluctuations in the reported instantaneous radiation output rate, if this quantity is not smoothed over a time window containing many pulses. Since output rate is used not only to provide an indication to the user of current output rate, but also for feedback purposes and to trigger error conditions (treatment interlocks), having a stable measurement of output rate is critical to system performance. Often, the smoothing window chosen to stabilize the output rate measurement is arbitrary and non-adaptive to the current delivery conditions as specified in the treatment plan. Therefore, it is desirable to provide systems and methods for pulse parameter (amplitude, pulse shape, pulse energy, pulse period and duty cycle) modulation to reduce or eliminate the inaccuracies and fluctuations in output radiation.